The present invention relates to an electrical switch for gas-burner lighters that can be associated to the body of a gas-supply cock.
In recent embodiments of cooking stoves with gas burners, it is known that an electrically operated gas-lighter, for example of the spark or incandescence type, can be associated to each burner, the gas lighter being operated by the user at the same time as he operates the gas-supply cock of the chosen burner.
The supply cock is in fact controlled by a maneuvering stem, which, being constrained in such a way that it is free to slide and turn along and about its own axis with respect to the body of the cock, enables supply of the amount of gas desired by the user when it is pressed against the body of the cock and rotated with respect to the latter.
The electrical circuit of the gas-lighter is then connected to a switch which is, in turn, operatively connected to the] maneuvering stem of the supply cock, in such a way that the pressure exerted by the user on the stem to deliver the gas involves closing of the switch, and the simultaneous operation of the lighter, whilst release of the [said] stem involves opening of the switch.
Such switches for gas-burner lighters are generally made up of a box-like shell that is connected to the cock body, two electrical contacts set at a distance apart and belonging to the circuit of the lighter, and a mobile body for closing the circuit, which, being constrained in such a way that it is free to slide in the shell, can be pushed by the maneuvering stem of the cock itself.
In a particular known switch, both the shell, which is engageable with the body of the cock, and the mobile body, which is translatable with respect to the shell, have a circular hole within which, during assembly, is inserted the maneuvering stem of the cock. Furthermore, within the shell, the two electrical contacts, appropriately shaped, are set one above the other and at a distance apart from one another in the case unless they are subjected to an external force. When pressed for gas supply, the maneuvering stem, induces, by means of a contrasting element, a displacement of the mobile body towards the inside of the shell, in such a way that the mobile body in turn pushes, by deforming it elastically, one of the two electrical contacts against the other to close the circuit of the lighter. When the maneuvering stem is instead released, one or more return springs, acting on the mobile body within the shell, push the [said] mobile body to return to its initial position, thus opening the circuit.
Although the switch is simple to assemble on the stem, it requires the presence of elastic means for return of the mobile body into its initial position, for the purpose of enabling opening of the circuit. This involves a certain constructional complexity of the switch and can lead to the malfunctioning of the switch itself when the springs, on account of possible permanent set due to use, are no longer able to perform their return function correctly.
In addition, the arrangement and mutual connection of the two contacts, on account of elastic deformation of one of these when subjected to the force of the mobile body, can produce, over time, a lasting deformation that keeps the two contacts permanently connected, and hence the circuit of the lighter closed.
In another known embodiment, the switch comprises an external shell that is fixed to the body of the supply cock, and a control rod, i.e., a mobile body, that is free to slide within the external shell. The control rod has one end that can be pressed by a knob or collar that is integral with the maneuvering stem of the supply cock, whilst the other end is provided with an electrically conducting element. Inside the shell the electrical contacts are separated from one another, and closing of the circuit of the lighter occurs when, following upon translation of the control rod, the conducting element of the control rod engages with the two electrical contacts. When the maneuvering stem is released, elastic means anchored within the shell push the control rod into its initial position, thus interrupting the connection between the contacts, and hence opening the circuit of the lighter.
Also in this type of switch, the presence of the return springs leads to problems regarding the constructional complexity and to the operation of the switch which deteriorates over time; i. e., problems that are similar to the problems referred to in the embodiment described previously.
In addition, the arrangement of the control rod within the external shell must be particularly precise dimensionally to prevent possible misalignments between the end portion of the rod provided with the electrical conductor and the two separated contacts. Such a misalignment could lead to the impossibility of connecting the contacts together, and thus closing the circuit of the lighter.
One purpose of the present invention is to solve the problems existing in the known art by providing an electrical switch for a gas-burner lighter that is simple to make and that proves reliable and effective also given a high frequency of use.
A further purpose of the present invention is to provide a switch for gas-burner lighters that is compact, simple to install, and that does not involve particular constructional precautions to prevent misalignments between the parts.
The electrical switch of a lighter for gas burners, according to the present invention, may be associated to a gas-supply cock of the type comprising a maneuvering stem that is free to slide and turn about its own axis within the body of the cock to control gas supply.
The switch comprises an external shell that can be fixed to the body of the cock, which in turn encloses a first contact and a second contact that may be connected together to close or to open the electrical circuit of the lighter. The switch is likewise provided with a control rod, which is free to slide within the shell, and is constrained to the maneuvering stem in such a way as to translate, but not to rotate, in an integral way with the stem, in the two directions of translation of the stem itself. The control rod is able to set the two contacts in electrical connection in correspondence to at least one position of the stem, whilst the two contacts are otherwise separate from one another.
According to a preferred aspect of the present invention, at least one of the two contacts is pushed in closing against the other contact, and the control rod comprises an insulating portion that can be set between the two electrical contacts to interrupt the circuit of the lighter in correspondence to one or more positions of the maneuvering stem.
According to a further aspect of the present invention, the control rod comprises both an insulating portion, and a portion for closing the contacts, which can alternatively be set between the contacts themselves to open or to close the circuit of the lighter, according to the position assumed by the maneuvering stem.
According to a further aspect of the invention, one of the contacts of the switch is elastically connected in closing to the other contact, and the closing portion of the control rod comprises a connecting window for the aforesaid contacts.